Method of producing resinous copolymers in situ on fabrics



March 3, 1959 F. M. FORD 2,876,136

METHOD OF PRODUCING RESINOUS COPOLYMERS IN SITU 0N FABRICS Filed March20, 1957 3 Sheets-Sheet 1 fig 1.

PVA AT LE THERMOSETTING WATER METHYLOL CATALYST 90% HYDROLYZED RESIN(TMR) FORM sownou OF PVA AT :95 zlz F2 COOL PVA SOLUTlON TO \26F. 0RLOWER AT \2.5F. m snow FORM soumou OF PVA AND TMR AT I25F. 0R BELOWMECHANICAL FINISH (OPTIONAL) CURE TO FORM WATER INSOLUBLE. COPOLYMER 0FPVA BLTMR INVENTOR FLORENCE M- FORD ATTORNEY!) March 3, 1959 F. M. FORD2,876,136

METHOD OF PRODUCING RESINOUS COPOLYMERS IN SITU 0N FABRICS Filed March20, 1957 3 Sheets-Sheet 2 fig. Z.

PVA THERHOSETTING AT LEAST 50% WATER METHYLOL REsm CATALYST HYOROLYZEO(TMR) WHY TO FORM SOLUTlON PURE IMPREGNATE FABR\C FABR\C ADJUST RESINP\CK-UP To DEPOSIT 2'87!) RESIN SOL- 5 0N FABRlC.

ADJUST MOISTURE CONTENT OF FABRIC TO 7% To 14% CALENDER CURE TO FORMWATER NSOLUBLE.

COPOLYME OF PVA 0- 'EPIR INVENTOR FLORENCE M. FORD WV'M ATTO R N EYSMarch 3, 1959 F. M. FORD METHOD OF PRODUCING RESINOUS COPOLYMERS IN SITUON FABRICS Filed March 20, 1957 3 Sheets-Sheet 3 TEERHOSETT'ING Y ATLEAST WATER METHYLOL RESIN (.ATAL-Ysl' 50 uvonourzeo (TMR) Mm To FORMsownorq PVA L 1 T MR 5 67 FRAGILE mam IM REGNA 4 ;/s dmss FABRKC ADJU5TRESIN PICK-UP TO uavogrr 1104.5 ESIN SOLIDS ON FABRIC CURE TO FORM WATERINSOLUBLF.

(.0 POLYMER OF PvA & TM R ADJUST MOISTURE CONTENT T0 l2. To 20% CALENDER(LURE TO FORM WATER IN5OLUBLE COPOLYHER INVENTOR FLORENCE M. FORDATTORNEY5 United States Patent METHOD OF PRODUCING RESINOUS COPOLY- MERSIN SITU ON FABRICS Florence M. Ford, Wilmington, Del., assignor toJoseph Bancroft & Sons Company, Wilmington, Del., a corporation ofDelaware Application March 20, 1957, Serial No. 647,193 6 Claims. (Cl.117-65) This invention relates to the art of applying textile finishingagents to and fixing such agents on textile fabrics, especiallycellulosic fabrics in woven or knitted form, made, for example, fromcotton, regenerated cellulose, linen or mixtures thereof.

As schematically illustrated in Figure l, of the accompanying drawing,the invention is particularly applicable to the kind of fabric finishingtreatment in which an impregnating solution containing the constituentsto be permanently retained by the fabric is preliminarily prepared froma very highly hydrolyzed polyvinyl alcohol, and is then applied to thefabric, as by padding, following which the fabric is treated to cure orset resinous constituents incorporated in the impregnating solution.Other fabric finishing steps may also be involved, such, for example, ascalendering, in which event the curing of the resinous constituents onthe fabric may serve to render durable not only the hand and othercharacteristics contributed by the impregnating constituents retained bythe fabric, but also the finish imparted by the calendering.

It is contemplated according to the invention to employ certainparticular interreactable resinous constituents in the impregnatingsolution, and the invention has in view, as a general objective, asequence of steps ensuring copolymerization or interreaction of theinterreactable constituents in situ in and on the fibers of the fabric,rather than at an earlier stage of the processing, notwithstanding thefact that the interreactable constituents are preliminarily intermixedin a common aqueous medium prepared as an impregnating solution.

More specifically, the invention contemplates employment, as twointerreactable resinous constituents, of polyvinyl alcohol and analdehyde compound in the watersoluble precondensate state.

The aldehyde precondensate may be a methylol urea, methylol melamine, orketone aldehyde, specific examples of which are dimethylol urea,dimethylol melamine, methylated dimethylol melamine, dimethylol ethyleneurea, urea formaldehyde, sesquimethylol urea, and dimethylol acetone.

It is further contemplated according to the invention that thesecompounds be employed in the precondensate or partially condensed form,rather than using the constituents merely capable of yielding suchprecondensates, for the reason that a compound such, for example, asfree formaldehyde, if present in the impregnating solution, willpreferentially react with the polyvinyl alcohol, thereby precluding orat least impairing the type of reaction product desired to be present onthe fabric after curing, i. e., the co-polymer of the polyvinyl alcoholand the aldehyde precondensate.

The aldehyde compounds, although preliminarily condensed. so to speak,are nevertheless relatively readily reactable with polyvinyl alcohol,and with this consideration in mind, one aspect of the inventioncontemplates preparation of the impregnating solution from asubstantially completely hydrolyzed polyvinyl alcohol (most desirablyabove about 90% hydrolyzed) and application of 2,876,136 lcg PatentedMar. 3, 1959 the solution to the fabric in accordance with the techniquedescribed herebelow, in order to ensure co-polymerization of the tworesinous constituents in and on the fibers of the fabric, rather than atan earlier stage of the processing.

It is here pointed out that it is of importance to effect completedissolution of the polyvinyl alcohol in the aqueous medium of theimpregnating solution, but that with the substantially completelyhydrolyzed polyvinyl alcohol (which is highly reactive with respect tothe aldehyde precondensates), dissolution of the polyvinyl alcohol canonly be effectively attained at relatively high temperatures such that,if the aldehyde precondensate is also present, interreaction will tendto occur, and in addition, the molecules of the precondensate would alsotend to further polymerize, both of which effects result in theimpairment of the desired ultimate reaction of the polyvinyl alcohol andprecondensate on the fabric itself.

With all of the foregoing in mind, the invention contemplates initiallydissolving the substantially completely hydrolyzed polyvinyl alcohol ina portion of the aqueous medium to be employed in making up theimpregnating solution and the effecting of the dissolution of thepolyvinyl alcohol at an elevated temperature, preferably above 185 F.After complete solution of the polyvinyl alcohol has been obtained, thisportion of the impregnating solution is cooled, preferably to atemperature below F., whereupon it is intermixed with an aqueoussolution of the aldehyde precondensate, together with such otherconstituents as may be desired in the impregnant, such, for example, asa textile softener, a textile lubricant, or the like.

In formulating the impregnating solution from substantially fullyhydrolyzed polyvinyl alcohol, the amount of polyvinyl alcohol inrelation to the amount of the aldehyde precondensate may be varied overa wide range. Thus the polyvinyl alcohol may be used in an amountsubstantially equal to the amount of the aldehyde precondensate, or maycomprise only a minor fraction of the amount of the precondensate, evendown to 1 part of polyvinyl alcohol to 125 parts of the precondensate.

In the preferred practice of this aspect of the invention, where asolution pick-up of 60% to 70% is employed, the solution is prepared tocontain a concentration of from .I% to about 3% of the polyvinyl alcoholand from about 3% to about 12.5% of the aldehyde precondensate, both byweight of the total solution.

The solution is then applied to the fabric while still at a temperaturebelow about 125 F., for instance, by padding, and after impregnation,the fabric may be squeezed to yield a solution pick-up of from about 60%to 70% by weight of the fabric.

Other processing or finishing steps may then be employed, such ascalendering, but whether or not such other processing steps areemployed, the fabric is ultimately heated to effect co-polymerization ofthe polyvinyl alcohol and of the aldehyde precondensate in and on thefibers of the fabric. At the time of curing, the total amount of theprecondensate and polyvinyl alcohol resin solids on the fabric should bebetween about 2% and 10% by weight of the fabric.

The curing is preferably effected by subjecting the fabric to atemperature of from about 250 F. to about 450 F. for a time of about 10minutes to 1 minute.

During the curing, a catalyst promoting interreaction of the polyvinylalcohol and the aldehyde precondensate should also be present. Such acatalyst is desirably incorporated in the impregnating solution and, ifthe conditions of preparation of the solution and its use, as describedabove, are observed, such presence of the catalyst in the impregnatingsolution will not impair the desired ultimate result, i. e., theco-polymerization of the resinous constitucuts on the fabric. However,as disclosed in U. S. Patent No. 2,242,218 and British Patent No.450,225, the catalyst can be introduced in a separate operation.

Examples of catalysts which may be used are ammonium thiocyanate,stearamidomethyl pyridinium chloride, and 2-amino-2-methyl-l-propanolhydrochloride. Various other catalysts which are known in the art topromote condensation reactions of this general type may be used. Thesemay be either acidic or alkaline, depending upon the nature of the resinprecondensate employed.

By operating according to the foregoing technique, the invention assuresthat co-polymerization of the substantially fully hydrolyzed polyvinylalcohol and the aldehyde precondensate is effected on the fabric itself,and I have found that maximizing this co-polymerization in this wayminimizes the total quantity of resinous constituents which need beapplied to the fabric to secure given finishing results, especially withrespect to the durability of the finish effect. This is of advantagesince, in general, the use of increasing quantities of resinousconstituents tends to tender or weaken the fabric.

Moreover, the technique of the present invention also substantiallycompletely overcomes the tendency for the development in theimpregnating solution, on the impregnated fabric, and on fabric handlingand finishing equipment, such as calender rolls, of granular deposits ofpartially polymerized resinous constituents or of interreaction productsof the polyvinyl alcohol and the aldehyde precondensate.

Figure 1 schematically illustrates this aspect of the invention.

As schematically illustrated in Figure 2, another aspect of theinvention is especially concerned with production of durable calenderfinish effects, and particularly with calendering operations employingso-called high pressure calenders.

This aspect of the invention is also applicable to woven or knittedtextile goods made of cellulosic materials, particularly cotton,regenerated cellulose, linen, and mixtures thereof.

It is known in the production of calender finishes that durability maybe imparted if the fabric is impregnated with certain resins or resinousmaterials, prior to the calendering operation, such resinous materialsbeing cured or set to thereby retain the finish effect.

This aspect of the invention has several general objectives in view,including making possible the attainment of a given type of highpressure calender finish effect of high durability with less totalresinous materials on the fabric. This is important since the presenceof the resinous materials cured on the fabric has a tendency to weakenthe fabric.

In addition, it is common in most prior calender finishing operations topreliminary size the fabric by applying thereto some agent addingstiffness or body to the fabric. In accordance with the presentinvention, such pre-sizing is not needed, since the process of thepresent invention, especially by virtue of the selection and applicationto the fabric of certain particular resinous materials, produces afabric of good hand and body, notwithstanding the absence of presizing.

The foregoing and other objects and advantages of this aspect of theinvention will appear more fully from the following description in whichreference is first made to a typical or illustrative operation accordingto the invention.

A woven cotton fabric, for example, 80/803.50 yd./lb., in the purestate, i. e., without pre-sizing materials to stiffen or add body to thefabric, is first impregnated with an aqueous solution containing thefinishing agents to be permanently retained by the fabric. According tothe invention. this impregnating solution contains certaininterreactable resinous finishing constituents, as defined more fullyhereinafter, the fabric is then dried to a moisture content below avalue referred to herebelow. The dried fabric is then passed to andthrough a high pressure calender, for example, a schreiner calender,following which the fabric is heated to cure or set the resinousmaterials, in this instance to effect copolymerization of theinterreactable constituents present in the impregnant.

With the foregoing general outline of the processing procedure in mind,attention is now directed to various criteria and conditions which areto be observed in the practice of this aspect of the invention.

First with respect to the pure state of the fabric referred to above,the invention contemplates application of the several treatment steps toa fabric which has been subjected to the usual treatments employed inpreparation of the fabric for finishing, except for the omission of thepre-sizing with stiffening agents. Thus, in preparing the fabric, it issubjected to singeing, usually also to a de-sizing operation to removestarch or lubricant applied during weaving or the like. Scouring isusually also used to saponify and remove waxes and oils. The fabric isalso usually bleached and may be either dyed or undyed. The referenceherein to pure" fabric refers to fabric prepared by application of theseknown treatment steps.

The pure fabric is then impregnated with the aqueous impregnatingsolution containing the interreactable resinous constituents abovementioned.

With respect to the polyvinyl alcohol to be employed, it is preferred toutilize a polyvinyl alcohol having a degree of hydrolysis of at leastabout 50%. If the polyvinyl alcohol used is the highly reactive,substantially fully hydrolyzed (e. g. over about form which can only bedissolved at relatively high temperatures, the solution should beprepared and applied as previously described. The more soluble, lessreactive forms of polyvinyl alcohol can of course be incorporated in thesolution in the usual manner. Further, in connection with the polyvinylalcohol constituent, it is to be observed that it is essential to employpolyvinyl alcohol itself, because various other alcohol compounds do notafford the multiple hydroxyl groups which are essential to effect theformation of the co-polymer with the aldehyde precondensate alsoemployed.

In formulating the impregnating solution for use in calender finishingoperations, the amount of the polyvinyl alcohol should be from about 33%to about 0.8% of the amount of the aldehyde precondensate present. Foran impregnating operation when 60 to 70% solution pick-up is used, theresinous precondensate should be employed in an amount from about 3% toabout 12.5% by weight of the solution, and the polyvinyl alcohol shouldbe employed in an amount from .1% to 1% by weight of the solution.However, as is well understood in the art, if it is desired to operatein a different pick-up range, the solution concentration should bevaried so as to provide the fabric with a total resin solidsconcentration of from about 2% to about 8% of the weight of the fabric.

Other constituents may also be present in the solution, but it ispreferred that the sum of the precondensate and the polyvinyl alcoholshould constitute at least 90% by weight of the interreactableconstituents of the solution. Moreover, it is further preferred that thesum of the precondensate and the polyvinyl alcohol should constitute atleast the major part of the total of those finishing agents incorporatedin the solution which are to be retained permanently on the fabric.These limitations are of importance in order to ensure that theinfluence and effect of the co-polymer to be produced on the fabricpredominates, and is not impaired by adverse influences such as havebeen encountered herebefore.

After formulation of the impregnating solution, it should be retained ata temperature below F. and should be applied to the fabric withoutelevation of temperature beyond about 125 F. in order to minimizeformation of the co-polymer until after the mechanical finishing has atleast been initiated, i. e., until the goods enter the calender. This ismost important where the substantially fully hydrolized form ofpolyvinyl alcohol is used.

The impregnation of the fabric with the prepared solution may beeffected by any of the well known impregnating techniques, for instance,by padding.

Following the impregnating operation, the fabric is desirably subjectedto a drying operation of sufiicient extent to reduce the moisturecontent of the fabric to below 14% by weight, and the fabric should befed to the calender at a moisture content below the 14% limit justmentioned. In the preferred operation according to the invention. thefabric, at the time it is fed to the calender, should have a moisturecontent of from between 7% to 14%. It is important not to exceed amoisture content much above 14% because under those conditions, resinousconstituents may be squeezed out of the fabric and onto the rolls of thehigh pressure calenders here contemplated for use. It is desirable notto reduce the moisture content much below 7% because there is apossibility of prematurely initiating co-polymerization of theinterrcactants mentioned prior to calendering unless some moisture ispresent to prevent excessive rise in temperature. As will be pointed outhereinafter, when a fragile fabric is to be calendered, a generallyhigher moisture content should be utilized.

At the time of feeding the fabric to the calender, it is preferred thatthe total amount of the aldehyde precondensate and the polyvinyl alcoholresin solids be from about 2% to about 8% by weight of the fabric.

The invention, as already mentioned, is particularly concerned withtreatments involving calendering by means of high pressure calenders, i.e., calenders operating at a roll pressure upwards of about 10 to tons,this pressure being calculated by addition of the pressure applied tothe roll bearings, at the two ends of the roll.

Calenders of the high pressure type operate at roll pressures running upfrom about 15 tons to well above 100 tons, and include such calenders asglazing calenders, schreiner calenders, chasing calenders, rollingcalenders, and embossing calendars.

With the high pressure calenders generally, and especially with certainof them, the high pressure has a tendency to increase the stiffness orboardlike character of the finish, but I have found that by maintainingthe content of the polyvinyl alcohol at a relatively low value,preferably below about 1% of the impregnating solution (based on 65%solution pick-up), desirable fabric finishes may be obtained with theuse of high pressure calenders, even where the pressure is very high andeven when employing certain particular types of calenders whichheretofore have a tendency to undesirably exaggerate the stiffness ofthe fabric. This is especially true with respect to the schreinercalender, which is operated above a roll pressure of about 25 tons, andwhen employing the schreiner calender the invention contemplateslimiting the polyvinyl alcohol content of the impregnating solution to amaximum of about 5% (with 65% solution pick-up).

It is here further pointed out that when operating according to theinvention, high pressure fabric finishes of. good hand and of a givendegree of durability may be obtained with appreciably less total contentof resinous constituents in the impregnating solution and on the fabricthan has been possible heretofore where resinous precondensates alonehave been employed in the impregnating solution.

With respect to the heating to be applied in order to cure or set theresinous constituents, it is first noted that it is important accordingto the present invention that the polyvinyl alcohol and also thealdehyde precondensate be present in form or state capable of readyinterreaction during the heating operation. Thus, for this purpose, itis not only of importance to employ polyvinyl alcohol having a degree ofhydrolysis of at least about 50%, but

' also to employ aldehyde precondensates which are not garded as beingthe full equivalent of a urea-formaldehyde.

precondensate. That is not true of the present operation. If substantialquantities of free formaldehyde are present. the formaldehyde willpreferentially react with the polyvinyl alcohol to produce an insolublereaction product and thereby preclude pro tanto the formation of theco-polymer which is the intended reaction product of the presentinvention.

With further reference to the heating, it should be kept in mind that atleast some of the heating to effect eopolymerization of the polyvinylalcohol and the aldehyde precondensate may occur during the calenderingoperation itself, especially in the case of chasing calenders, or otherequipment in which the fabric requires some appreciable time to passtherethrough and in which elevated temperatures are employed. Similarly,in the case of certain friction glazing treatments where the fabric ispassed through the glazer a plurality of times, at least someappreciable extent of the desired co-polymerization may occur during thecalendering operation itself and, in fact, depending upon the operatingconditions and the number of passes through the equipment, it is evenpossi ble to substantially completely eo-polymerize or set the resinousconstituents without the necessity for applying a subsequent andseparate heat treatment.

Regardless of the manner in which the heating is cffected, it isdesirable that the fabric be subjected to a temperature of from about250 F. to about 450 F. for a time of about 10 minutes to 1 minute.

Other ingredients may be added, in conventional amounts, to thesolution, such as a conventional textile softener, a conventionaltextile lubricant (or a softener which is also a lubricant), dependingupon the particular hand and feel desired and/or to lubricate calendersurfaces. A conventional textile water repellent may also be added.Where such an additional ingredient is employed, I may use Zelan(stearamido-methyl pyridinium chloride, manufactured by E. I. du Pont deNemours & Co., Wilmington, Delaware) along with the polyvinyl alcoholand the aldehyde precondensate for the reason, among other things, thatthe Zelan in this process is a catalyst, a softener, a water repellent,and a lubricant.

The use of a lubricant is particularly desirable in certain operations,especially where a calender, such as a glazing calender, is employed inwhich a roll surface is caused to slip on the surface of the fabric.

Among the various treatment conditions and factors of importance inachieving the various objectives already mentioned, theco-polymerization of the polyvinyl alcohol and the aldehydeprecondensate on the fabric itself is of great importance. Certain ofthe reasons for this are brought out just below.

Polyvinyl alcohol will not itself insolubilize or lose itsdispersibility on curing. Generally considered, it is a long carbonchain with hydroxyl or other groups attached to every second carbon, thenumber of hydroxyl groups depending on the degree of hydrolysis. One ofthe functions of the aldehyde precondensate is to insolubilize ordestroy the dispersibility of the polyvinyl alcohol by forming aco-polymer therewith on curing.

It may also be mentioned that polyvinyl alcohol alone or in percentagessubstantially above 1% would tend to give a leathery hand which would bedestroyed on washing, whereas the aldehyde precondensate alone wouldnormally tend to give a somewhat brittle hand. With the eo-polymer whichis formed on curing, there is a tendency for these two constituents tomodify one another so as to give a somewhat tough but flexible hand,

not brittle or harsh. The polyvinyl alcohol is a mixture of molecules ofvarious sizes, only the smaller ones of which will enter into the fibersof the fabric. n the other hand, the aldehyde precondensate comprisesrelatively small molecules, a large proportion of which will enter intothe fibers of the fabric. The co-polyrner formed will, therefore, bepartly within and partly on the surface of the fibers. In any event, theco-polymer provides a high degree of durability of the mechanical finisheffect contemplated according to the invention. It has been supposedthat direct reaction with the aldehyde precondensate with the cellulosemay also occur, for instance, by replacement of some hydroxyl groups ofthe cellulose and a cross-linkage between cellulose molecules, butwhatever may be the actual mechanism of the reaction, the effect is torender the cellulose nonswelling to water, and to provide highly durablefinishes.

As schematically illustrated in Figure 3, still another aspect of thisinvention relates to the production of durable finish effects on fabricsand is especially concerned with the production of effects on fragilefabrics made of cellulosic materials, particularly cotton, regeneratedcellulose, linen and mixtures thereof. What are herein referred to asfragile fabrics are fabrics of relatively light weight per square yard,i. e., weighing not more than about 4 ounces per square yard, andespecially those weighing less than 2.5 ounces per square yard, examplesof such fragile fabrics being voile, mousseline, lawns, etc.

It has been known in various fabric finishing operations, such as, forexample, crease proofing, calendering, etc., to apply to the fabriccertain resinous materials for the purpose of fixing and renderingdurable the finish effect. Various of the prior art finishingtechniques, while resulting in a relatively durable effect, have atendency to weaken or tender the fabric. This weakening effect tends toincrease with the quantity of resinous material applied to the fabric,and I have found that this is especially true with respect to fragilefabrics of the kind above mentioned.

According to this aspect of the present invention, the particularinterreactableresinous materials previously described are used invcombination and I have found that thereby a given degree of durabilityof the finish applied to fragile fabrics may be obtained withconsiderably smaller total quantities of resinous materials applied, inview of which a given degree of durability may be obtained with muchless tendering or weakening of the fabric than has been possibleheretofore.

In cases where it is desired to impart a mechanical finish effect tofragile fabrics, there has heretofore been a tendency, especially withcertain of the calender effects, for example, glazing (where rollslippage is present) for the fabric to be damaged, as by excessivedistortion of the weave or even tearing or chewing the fabric. Inaccordance with the present invention, how ever, when employing thecombination of resinous materials contemplated, it is practicable andpreferred to employ a somewhat increased moisture content in the fabricat the time of the calendering, and as a result of this the tendency todamage the fragile fabric by the calendering operation is greatlyreduced.

In a typical illustrative treatment according to this aspect of theinvention, a cotton lawn weighing about 21 3 ounces per square yard isimpregnated with a solu tion containing a water soluble resinousprecondensate and polyvinyl alcohol, together with a catalyst. Theimpregnated fabric is dried to a moisture content below about 20% byweight of the fabric and while the fabric is at a moisture contentbetween about 12% and 20%. it is passed to and through a glazingcalender. After glazing, the fabric is heated at a temperature and for atime sufficient to effect interreaction of the two resinous constituentsand thus form a water insoluble co-polymer in and on the fibers of thefabric.

With certain exceptions, as will be pointed out hereinafter, theforegoing discussion in connection with calender finishing aspects ofthe invention and with respect to the preparation of the impregnatingsolution, its components, its application to the fabric, and theultimate setting of the finish effect, also apply to the application ofthe invention to the finishing of fragile fabrics.

In formulating the impregnating solution for the finishing of fragilefabrics, somewhat different resin ratios and concentrations areemployed. The amount of the polyvinyl alcohol should be from about 33%to about 1.5% of the weight of the aldehyde precondensate present. Foran impregnating solution where 60% to 70% solution pick-up is used, thepolyvinyl alcohol should be employed in an amount from 0.1% to 1% byweight of the solution, and the resinous precondensate should beemployed in an amount from 3% to 6% by weight of the solution.

Following the impregnating operation, the fabric is desirably subjectedto a drying operation of sufficient extent to reduce the moisturecontent of the fabric to below 20% by weight, desirably between 7% and20%. When calendering is employed, it is preferred to feed the fabric tothe calender, at a moisture content of from between 12% and 20%.

At the time of feeding the fabric to the calender, it is preferred thatthe total amount of the aldehyde precondensate and the polyvinyl alcoholbe from about 2% to about 4.5% by weight of the fabric.

Whether or not mechanical finishing is used, the fabric should be heatedto effect the interreaciton of the resinous constituents in order toform a reaction product of the aldehyde precondensate and the polyvinylalcohol in and on the fibers of the fabric, as previously described.

Since as previously described, the co-polymer formed will be partlywithin and partly on the surface of the fibers, it provides a highdegree of crease resistance and of durability of the finish effectcontemplated according to the invention, notwithstanding the use ofrelatively small total amounts of resinous materials.

When employing the technique of the present invention, it is possible toobtain a given degree of durability of the finish effect (creaseresistance and/or calender finish) with appreciably less total resinousmaterial applied to the fabric, in many cases the reduction being of thegeneral order of 15 to 20%. With such reduction in the total amount ofresinous material applied, it is found that weakening of the fabric isgreatly reduced in many instances by as much as 25%, i. e., 25% lessthan has been encountered heretofore with other resinous finishingoperations adapted to obtain comparable durability. At the same time,the hand of the fabric is unusually good and quite distinctive.

Various of these improvements contemplated by the various aspects of theinvention will be illustrated in examples given hereinafter.

Example I A dyed cotton fabric having a construction of /80 and 4 yardsper pound was impregnated with the following solution and thereaftersqueezed to provide a solution pick-up of 65% by weight of the fabric:

Water to make parts.

The fabric was then dried to moistness (about 8% free moisture) and waspassed twice through a friction calender operating at a speed of 30yards per minute,

with the steel rolls heated to 370 F. and a pressure of 25 tons wasapplied, using a friction ratio of 2.5 to 1. The fabric was then curedat about 265 F. for about 2% minutes, and was washed and dried.

This treatment provided a fabric having a highly durable, highly glazedmechanical finish, with excellent strength, and of very good band,notwithstanding the fact that the total resin content employed was verysubstantially less than what would be required to give similardurability without the presence of polyvinyl alcohol. Moreover, thisresult was achieved without substantial loss in strength,notwithstanding the fact that the fabric was not pre-sized before thetreatment.

Example II The same fabric as referred to in Example I was treated inthe same way as in Example I except that the following impregnatingsolution was used, instead of that employed in Example I.

Water to make 100 parts.

The finish obtained by this treatment was similar to that obtained inExample I, notwithstanding the fact that the polyvinyl alcohol contentwas much less than in Example I, but in Example 11 the finish wassomewhat softer.

Example III A dyed cotton fabric having a construction of 80/ 80 and 4yards per pound was impregnated in the following solution and squeezedso that the fabric retained a 65% solution pick-up:

Parts Methylol melamine (100% solids) 5.4 Methylated methylol melamine(100% solids) 2.5 Polyvinyl alcoh 1.0 Sulfonated castor il 2.1

Methylhydroxypropanolamine hydrochloride 1.2 Water to make 100 parts.

The fabric was then dried to approximately 8% total moisture, and waspassed once through an embossing calender operating at a speed of 18yards per minute, with the steel roll heated to 400 F. and a pressure of18 tons was applied. The fabric was then cured at about 285 F. for about2% minutes.

A very sharply defined pattern was obtained and the finish waspermanent, of good hand, strength, abrasive resistance and stabilizationagainst shrinkage. The presence of the polyvinyl alcohol substantiallyeliminates tendency for the resinous materials to stick on the engravedroll and as a result, sharper definition of the design is obtained thanin a similar treatment in the absence of polyvinyl alcohol, even with anincrease in the quantity of the aldehyde precondensates.

The treatment of this example was repeated with changes in the type ofcalender employed, in one instance a shallow engraved embossing calenderwas used, in another instance a moire calender was used, and in a thirdinstance a schreiner calender was used. Comparable results were obtainedin each instance and in no case was there tendency for the resin tostick to the calender rolls, so that the rolls could be run for longperiods of times between cleanings.

The treatment above described was repeated with different curingtemperatures and times. In one repetition, a temperature of 450 F. and atime of 1 minute was used, and in another instance a temperature ofabout 250 F. and a time of 10 minutes was used. In all cases the resultswere comparable.

10 Example IV The same fabric was treated in the same manner as inExample III, except that the impregnating solution was as follows:

Parts Dimethylolethyleneurea (50% solids) 9.3 Polyvinyl alcohol 0.36Tetraalkylquaternary ammonium chloride 1.7

Methylhydroxypropanolamine hydrochloride 1.2 Water to make 100 parts.

The results obtained were similar.

Example V A printed-cotton fabric having a construction of /92 and 3.50yards per pound was impregnated in the following solution and was thensqueezed to a solution pick-up of 65 Methylhydroxypropanolaminehydrochloride 1.2 Water to make parts.

After drying to moistness, the fabric was passed through a chasingcalender, the metal rolls of which were heated to about 300 F. andoperated at a pressure of substantially 25 tons on the bearings, thecalender operating at a speed of yards per minute. After thecalendering, the fabric was cured at about 300 F. for about 2 /2minutes. A substantially permanent finish of excellent hand and strengthwith deep seated luster was obtained.

The treatment above described was repeated with different curingtemperatures and times. In one repetition, a temperature of 450 F. and atime of 1 minute was used, and in another instance a temperature ofabout 250 F. and a time of 10 minutes was used. In all cases the resultswere comparable.

Example VI An all spun regenerated cellulose fabric 46/40 and 3.50 yardsper pound was impregnated in the following solution and squeezed to asolution pick-up of 65%:

Parts Dimethylol ethylene urea (50% solids) 25 Stearamidomethylpyridinium chloride 1.4 Sodium acetate 0.24Methylhydroxypropanolamine hydrochloride 1.2 Polyvinyl alcohol 0.36

Water to make 100 parts.

A linen fabric was impregnated in the following solutron and wassqueezed to a solution pick-up of 65%:

Parts Dimethylol ethyleneurea (50% solids) 9.3 Polyvinyl alcohol 0.36Tetraalkylquaternary ammonium chloride 1.7 Methylhydroxypropanolaminehydrochloride 1.2

Water to make 100 parts.

After drying to a moisture content approximating 8% total moisture, thefabric was passed once through a calender operating at a speed of 18yards per minute, with the steel roll heated to about 400 F., and apressure of Example VIII A white cotton fabric, 4088/80 and 6.9 yardsper pound, was impregnated in the following solution and then squeezedto give approximately a 65% solution pick- Parts Methylated methylolmelamine (100% solids) 6 Polyvinyl alcohol 0.18s-Di[l-(2-stearoamidoethyl)lurea monoacetate 4.1

Methylhydroxypropanolamine hydrochloride 1.2 Water to make 100 parts.

The fabric was then dried to moistness (about 8% free moisture or about13% total moisture), and was passed twice through a friction calenderoperating at a speed of 30 yards per minute, with the steel roll heatedto 370 F. and a pressure of tons was applied, using a friction ratio of2.5 to l. The fabric was then cured at about 265 F. for about 2 /2minutes and then washed and dried.

A finish of high glaze was obtained and the fabric had excellentstrength being only slightly less than that obtained in Example XI. Theabrasion resistance and stabilization were excellent.

Similar permanent finishes with similar strength and othercharacteristics were secured by the same treatment as here described,except for varying the number of runs through the calender. With onlyone run through the calender, the gloss was good, though not as high aswith two runs, and with three runs through the calender, the gloss washigher than with two. In all cases, the degree of gloss was higher thanwith a comparable finishing operation employing the other resinconstituent in the absence of polyvinyl alcohol.

Example IX A white cotton fabric, 40"88/ 80 and 6.90 yards per pound,was impregnated in the following solution and then squeezed to giveapproximately a 65% solution pick-up:

Parts Methylated methylol melamine (100% solids) 3 Polyvinyl alcohol .12Sulfonated castor oil 2.00 Methylhydroxypropanolamine hydrochloride 1.2

Water to make 100 parts.

The fabric was then dried and cured in an oven having an atmosphere atapproximately 275 F. with a residence time of approximately 2 /2minutes. The fabric was then washed and dried.

A very durable crease-resistant finish was obtained with good band andstrength, with good abrasion resistance, and fairly good stabilization.

Example XI A white cotton fabric, 40"88/80 and 6.90 yards per pound, wasimpregnated in the following solution and then squeezed to giveapproximately a 65% solution pick-up:

Parts Methylol melamine solids) 4.3 Methylated methylol melamine (100%solids)-.." .8 Urea 2.4 s-Di[ I-(Z-stearoamidoethyl) lurea monoacetate.6 Methylhydroxypropanolamine hydrochloride 1.2 Polyvinyl alcohol .3

Water to make 100 parts.

The fabric was then dried and cured in an oven at a temperature ofapproximately 275 F. with a residence time of approximately 2% minutes.The fabric was then washed and dried.

A substantially permanent crease-resistant finish was obtained withnegligible loss in tensile strength, from substantially 41 warp and 26filling in the untreated control to substantially 38 warp and 25filling, representing an exceptionally small strength loss. The tearstrength of the fabric actually was increased, from substantially 586warp and substantially 425 filling in the control, to substantially 611warp and 480 filling. To obtain a similar substantially permanent finishin the absence of polyvinyl alcohol, the other resin constituent wouldhave to be increased at least 20%, in which case the strength would beapproximately 25% less, and the hand would be markedly interior. Thehand or feel obtained in accordance with this example (XI) is quitedistinctive, being full-bodied, but nevertheless soft. It will be notedthat this finish effect was secured notwithstanding the use of verysmall amounts of both polyvinyl alcohol and of the other resinousmaterial. The combined effect of these two constituents, which becomeco-polymerized in and on the fibers of the fabric, thus produces ahighly desirable finish with low loss of strength, as compared with asimilar treatment employing the other resin constituents in the absenceof the polyvinyl alcohol. The stabilization against shrinkage is alsosubstantially as good if not better, and the abrasion resistance is muchbetter than would be obtained in the absence of polyvinyl alcohol butemploying a larger amount of the other resinous constituents. Theprocedure of this example was repeated with variation in curing,temperature and time, with comparative results. Thus in one repetition,the curing was done at a temperature of about 450 F. with a residencetime of about one minute; and in another repetition, the curing was doneat about 250 F., with a residence time of about ten minutes.

Example XII Example XI was repeated on a difierent cotton fabric of thesame construction as in Example XI, with the sole exception that theimpregnating solution contained 0.625 part of polyvinyl alcohol insteadof .3 part.

The crease-resistant finish thus obtained was for all practical purposespermanent; the strength was even better than in Example XI; and thedistinctive hand,

while of still fuller body, was nevertheless still soft and pleasing. Inother respects, the results were comparable to those obtained in ExampleXI.

Example XIII The treatment procedure described above in Example XI wasapplied to the same cotton fabric, but a different impregnating solutionwas employed, as follows:

Water to make 100 parts.

The results were, in most respects, very similar to those obtained inExample XI, but the stabilization against shrinkage was even better.

13 Example XIV The procedure of Example XI fully described above wasrepeated but applied to a dyed cotton fabric having a construction of80/80 and 4 yards per pound. Similar results were obtained.

Example XV The procedure of Example XII fully described above wasrepeated but applied to a dyed cotton fabric having a construction of80/ 80 and 4 yards per pound. Similar results were obtained.

Example XVI The procedure of Example XIII fully described above wasrepeated but applied to a dyed cotton fabric having a construction of80/80 and 4 yards per pound. Similar results were obtained.

In all of the foregoing examples, the polyvinyl alcohol is at least 50%hydrolyzed, and polyvinyl alcohol which is substantially completelyhydrolyzed can be used provided the previously described specialtechniques for the preparation and application of impregnating solutionsprepared from such grades of polyvinyl alcohol are observed.

This application discloses and claims subject matter disclosed inapplicants pending applications as follows: Serial No. 287,590, filedMay 13, 1952; Serial No. 294,- 491, filed June 19, 1952; Serial No.296,090, filed June 27, 1952; Serial No. 647,191, filed March 20, 1957;or Serial No. 647,194, filed March 20, 1957.

I claim:

1. In the art of applying textile finishing agents to and fixing suchagents on textile fabrics, the method for effecting co-polymerization ona cellulosic fabric of interreactable finishing agents consistingessentially of polyvinyl alcohol and a water-soluble aldehyde resinprecondensate, which method comprises dissolving polyvinyl alcohol, atleast 90% of which is hydrolyzed, in water at a temperature betweenabout 185 F. and 212 F.,

cooling the polyvinyl alcohol solution thus formed to a temperaturebelow about 125 F., intermixing the cooled solution with a water-solublealdehyde resin precondensate selected from the group consisting ofmethylol ureas, methylol melamines and ketone aldehydes, the quantitiesof the intermixed resins providing a solution in which the ratio of.polyvinyl alcohol to said precondensate is from 1:1 to 1:125,maintaining the resin solution at a temperature below about 125 F. untilit is applied to the fabric, applying the solution to deposit on thefabric from 2 to total resin solids by weight and after application ofsaid solution to the fabric, heating the fabric in the presence of acatalyst at a temperature and for a time sufficient to effect theformation of a water-insoluble co-polymer of said interreactablefinishing agents.

2. In the art of imparting durable mechanical finishes to cellulosicfabrics involving impregnating the fabric with an aqueous solutioncontaining a mixture of resinous finishing agents to be retained by thefabric wherein said resinous mixture includes a water-solublethermosetting resin precondensate as one resinous component andpolyvinyl alcohol as a second resinous component, drying the fabric,calendering the dried impregnated fabric and heating the fabric in thepresence of a resin curing catalyst to fix the resinous finishingagents, the improvement characterized in that the polyvinyl alcohol isat least 50% hydrolyzed, the water-soluble thermosetting resinprecondensate is selected from the group consisting of methylol ureas,methylol melamines, and ketone aldehydes, the weight ratio of thepolyvinyl alcohol to the thermosetting resin precondensate ranges from1:3 to 1:125, the total combined weight of the polyvinyl alcohol and thethermosetting resin comprises at least of the inter-reactable materialspresent in the impregnating solution, and comprises the major portion ofthe finishing agents to be retained by the fabric, the total resinconcentration of the impregnating solution and the solution pick-up areadjusted to provide for applying to the fabric a total combined weightof the resin solids of from 2 to 8% of the weight of the fabric and theheating of the fabric is sufiicient to effect the formation of a waterinsoluble copolymer of polyvinyl alcohol and the thermosetting resin.

3. A process according to claim 2 and further characterized in that thefabric to be treated is a pure fabric, i. e. substantially free offabric stiffening sizing materials.

4. A process according to claim 2 and further characterized in that themoisture content of the fabric at the time the fabric is fed to thecalendar constitutes from 7 to 14% of the weight of the fabric.

5. A process according to claim 2 and further characterized in that theweight of the fabric to be treated runs not more than 4 ounces persquare yard; the weight ratio of the polyvinyl alcohol to thethermosetting resin precondensate of the impregnating solution and thesolution pick-up are adjusted to provide for applying to the fabric atotal combined weight of the resin solids which constitute from 2 to4.5% of the weight of the fabric; and the moisture content of the fabricat the time the fabric is fed to the calender constitutes from 12 to 20%of the weight of the fabric.

6. In the art of imparting durable finishes to cellulosic fabricsinvolving impregnating the fabric with an aqueous solution containing amixture of resinous finishing agents to be retained by the fabricwherein said resinous mixture includes a water-soluble thermosettingresin precondensate as one resinous component and polyvinyl alcohol as asecond resinous component, and heating the fabric in the presence of aresin curing catalyst to fix the resinous finishing agents, theimprovement characterized in that the weight of the fabric to be treatedruns 4 ounces per square yard and less; the polyvinyl a1- eohol is atleast 50% hydrolyzed; the water soluble thermosetting resinprecondensate is selected from the group consisting of methylol ureas,methylol melamines and ketone aldehydes, the weight ratio of thepolyvinyl alcohol to the thermosetting resin precondensate ranges from1:3 to 1:67, the total combined weight of the polyvinyl alcohol and thethermosetting resin comprise at least 90% of the inter-reactablematerials present in the impregnating solution and comprise the majorportion of the finishing agents to be retained by the fabric and thetotal resin concentration of the impregnating solution and the solutionpick-up are adjusted to provide for applying to the fabric a totalcombined weight of the resin solids which constitutes from 2% to 4.5% ofthe weight of the fabric and the heating of the fabric is sufficient toeffect the formation of a water insoluble copolymer of polyvinyl alcoholand the thermosetting resin.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Set. N0. 233,292, Schubert (A. P. C.), published May 4, 1943,now abandoned.

Rayon Textile Monthly, February 1948, pages 67-70.

2. IN THE ART OF IMPARTING DURABLE MECHANICAL FINISHES TO CELLULOSICFABRICS INVOLVING IMPREGNATING THE FABRIC WITH AN AQUEOUS SOLUTIONCONTAINING A MIXTURE OF RESINOUS FINISHING AGENTS TO BE RETAINED BY THEFABRIC WHEREIN SAID RESINOUS MIXTURE INCLUDES A WATER-SOLUBLETHERMOSETTING RESIN PRECONDENSATE AS ONE RESINOUS COMPONENT ANDPOLYVINYL ALCOHOL AS A SECOND RESINOUS COMPONENT DRYING THE FABRIC,CALENDERING THE DRIED IMPREGNATED FABRIC AND HEATING THE FABRIC IN THEPRESENCE OF A RESIN CURING CATALYST TO FIX THE RESINOUS FINISHINGAGENTS, THE IMPROVEMENT CHARACTERIZED IN THAT THE POLYVINYL ALCOHOL ISAT LEAST 50% HYDROLYZED, THE WATER-SOLUBLE THERMOSETTING RESINPRECONDENSATE IS SELECTED FROM THE GROUP CONSISTING OF METHYLOL UREAS,METHYLOL MELAMINES, AND KETONE ALDEHYDES, THE WEIGHT RATIO OF THEPOLYVINYL ALCOHOL TO THE THERMOSETTING RESIN PRECONDENSATE RANGES FROM1:3 TO 1:125, THE TOTAL COMBINED WEIGHT OF THE POLYVINYL ALCOHOL AND THETHERMOSETTING RESIN COMPRISES AT LEAST 90% OF THE INTER-REACTABLEMATERIALS PRESENT IN THE IMPREGNATING SOLUTION, AND COMPRISES THE MAJORPORTION OF THE FINISHING AGENTS TO BE RETAINED BY THE FABRIC, THE TOTALRESIN CONCENTRATION OF THE IMPREGNATING SOLUTION AND THE SOLUTIONPICK-UP ARE ADJUSTED TO PROVIDE FOR APPLYING TO THE FABRIC A TOTALCOMBINED WEIGHT OF THE RESIN SOLIDS OF FROM 2 TO 8% OF THE WEIGHT OF THEFABRIC AND THE HEATING OF THE FABRIC IS SUFFICIENT TO EFFECT THEFORMATION OF A WATER INSOLUBLE COPOLYMER OF POLYVINYL ALCOHOL AND THETHERMOSETTING RESIN.